The present disclosure relates generally to structures for surface enhanced Raman spectroscopy.
Raman spectroscopy is used to study the transitions between molecular energy states when monochromatic light interacts with molecules, which results in the energy of the light photons being shifted, or scattered. The energy shift provides information of the vibrational energy spacing in the molecular system. Surface enhanced Raman spectroscopy (SERS) enhances Raman scattering via molecules adsorbed on, for example, rough metal surfaces or metal nanoparticle aggregates. The Raman signal enhancement is typically related to the large electric fields generated near the metal surface due to localized surface plasmon resonance. However, the SERS signals strongly depend on the excitation light wavelength. To achieve a large Raman enhancement factor, the excitation light wavelength may be tuned in close proximity to the surface plasmon resonance of the rough metal surfaces or metal nanoparticles.